Error when Deleting Node from BST - c++

Question

This genuinely has me stumped. I have a binary search tree of citys that is ordered by the city name. A city also contains the population and GPS coordinates. I want to be able to remove nodes from the tree by City name or city coordinates. I have the delete by name working fine but the GPS coordinates does not work.
When I remove a node by GPS I get a stack-overflow when I try to print the binary tree. Below is some of my code. I cannot understand how it will work fine if I delete by name but not if I delete by coordinates as I am using the same delete method.
The exact error I get is "Unhandled exception at 0x013214D6 in EXE: 0xC00000FD: Stack overflow (parameters: 0x00000001, 0x00152FFC)." This occurs in my print function after I delete by coordinates but not if I delete by name.
bool BinaryTree::DeleteByName(string city)
{
if (GetRoot() != NULL)
{
return (DeleteByName(GetRoot(), city));
}
return false;
}
TreeNode* BinaryTree::DeleteByName(TreeNode *node, string city)
{
if (node == NULL)
{
return node;
}
else if (city < node->Data.name)
{
node->Left = DeleteByName(node->Left, city);
}
else if (city > node->Data.name)
{
node->Right = DeleteByName(node->Right, city);
}
else
{
if (node->Left == NULL && node->Right == NULL)
{
delete node;
node = NULL;
}
else if (node->Left == NULL)
{
TreeNode* temp = node;
node = node->Right;
delete temp;
}
else if (node->Right == NULL)
{
TreeNode* temp = node;
node = node->Left;
delete temp;
}
else
{
cout << "Else";
TreeNode* temp = MinPtr(node->Right);
node->Data = temp->Data;
node->Right = DeleteByName(node->Right, temp->Data.name);
}
}
return node;
}
bool BinaryTree::DeleteByCoord(pair<double, double> coords)
{
if (GetRoot() == NULL)
{
return false;
}
else
{
return DeleteByCoord(GetRoot(), coords);
}
}
bool BinaryTree::DeleteByCoord(TreeNode* node, pair<double, double> coords)
{
bool result;
if (node == NULL)
{
return false;
}
else
{
if (node->Data.coordinates.first == coords.first && node->Data.coordinates.second == coords.second)
{
return (DeleteByName(node, node->Data.name));
}
result = DeleteByCoord(node->Left, coords);
if (result == true)
{
return result;
}
return DeleteByCoord(node->Right, coords);
}
}
void BinaryTree::Insert(City city)
{
TreeNode* temp = new TreeNode(city);
if (GetRoot() == NULL)
{
root = temp;
}
else
{
Insert(temp, GetRoot());
}
}
void BinaryTree::Insert(TreeNode* toAdd, TreeNode* addHere)
{
if (toAdd->Data < addHere->Data)
{
if (addHere->Left != NULL)
{
Insert(toAdd, addHere->Left);
}
else
{
addHere->Left = toAdd;
}
}
else if (toAdd->Data > addHere->Data)
{
if (addHere->Right != NULL)
{
Insert(toAdd, addHere->Right);
}
else
{
addHere->Right = toAdd;
}
}
}
void BinaryTree::InOrderTraversal(TreeNode* node)
{
if (node != NULL)
{
InOrderTraversal(node->Left);
cout << node->Data << endl;
InOrderTraversal(node->Right);
}
}
void BinaryTree::InOrderTraversal()
{
InOrderTraversal(GetRoot());
}
TreeNode* BinaryTree::GetRoot()
{
return root;
}
TreeNode* BinaryTree::MinPtr(TreeNode* node)
{
while (node->Left != NULL)
{
node = node->Left;
}
return node;
}

Answer 1

When you delete the node you also need to update parent pointer that points to deleted node. Pay attention here:
when you call DeleteByName directly it searches required node and returns NULL pointer which automatically set to parent node pointer:
else if (city < node->Data.name)
{
node->Left = DeleteByName(node->Left, city);
}
else if (city > node->Data.name)
{
node->Right = DeleteByName(node->Right, city);
}
but when you call DeleteByName from coordinates method you do not reset parent's Left/Right pointers:
if (node->Data.coordinates.first == coords.first && node->Data.coordinates.second == coords.second)
{
return (DeleteByName(node, node->Data.name));
}
in its turn as DeleteByName already receives required node, it does not perform recursive call and does not reset parent's pointers either:
else
{
if (node->Left == NULL && node->Right == NULL)
{
delete node;
node = NULL;
}
//... same here
}
NOTE: There are many more problems in your code. Some that strike the eye:
DeleteByName returns pointer, but DeleteByCoord returns bool, you use pointer as a boolean type in DeleteByCoord
Avoid to compare doubles directly, the comparison result can be wrong. See the question and explanation for the details.